1. Field of the Invention
This invention relates generally to furniture and particularly to beds. Still more particularly this invention relates to articulating bed frames. Still more particularly, this invention relates to an articulating bed frame suitable for residential use.
2. Description of Prior Art
U.S. Pat. No. 6,006,379, which issued Dec. 28, 1999 to Hensley was cited as a reference in the parent application Ser. No. 11/699,759 referenced above. Hensley discloses an articulating bed frame in which a seat frame section of an articulating upper frame is fixed upon a carriage. The carriage is mounted on rollers arranged to roll along channels that are part of a base frame. An upper body frame section is pivotally mounted at one edge to an adjacent edge of the seat frame section. Support members extend between the upper frame section and the base frame to support the upper body section when it is horizontal. A drive system is provided for lifting and lowering the upper body frame section. The drive system includes an actuator having a first end pivotally connected to the base frame and a second end pivotally connected to the carriage. The drive system is arranged to move the carriage linearly along the channels. A linkage assembly has a first end pivotally connected to the base frame and a second end pivotally connected to the carriage. The linkage assembly is connected to the upper body frame section between the head end thereof and the pivot point where the upper body frame section and the seat frame section are connected together. When the actuator moves the carriage toward the head end of the frame, a support member of the linkage assembly is placed in compression and causes the upper body frame section to tilt upwardly from its horizontal position. This lifting action occurs because the portion of the upper body frame section between its pivotal connection to the seat frame section and the pivotal connection of the linkage to the upper body frame section acts as a lever arm to produce a torque about the pivot point of the upper body frame section relative to the seat frame section. The linkage assembly causes the upper body frame section to move back toward its horizontal position when the actuator moves the carriage toward the foot end of the frame. Without the linkage assembly, linear motion of the carriage caused by the actuator would exert no torque, or lifting moment on the upper body frame section. If the upper body frame section were lowered to a point where the link assembly is horizontal, the upper body frame section could not be raised again by linear motion of the carriage toward the head end of the frame.